Analyte monitoring devices and methods

ABSTRACT

On-body units are provided and include a transcutaneous analyte sensor, electronic circuitry electrically coupled to the sensor, and an on-body housing having electrical contacts disposed thereon. The on-body housing comprises a substantially flat surface and a curved and convex surface opposite the substantially flat surface. Systems and methods including the on-body units are also provided. Methods for performing continuity measurements using on-body units are also provided. The methods include positioning an on-body unit (OBU) on a skin of a subject, contacting a continuity test instrument to the OBU; and performing a continuity measurement with the continuity test instrument. An AC signal may be provided across two electrical contacts, or a DC signal may be provided across two electrical contacts in opposite directions for the same amount of time. The measurement may be performed with one electrical contact, or with isolated electrical contacts.

CROSS-REFERENCE TO RELATED APPLICATIONS

Pursuant to 35 U.S.C. §119(e), this application claims priority to U.S.Provisional Patent Application No. 61/477,489 filed on Apr. 20, 2011,the disclosure of which is herein incorporated by reference in itsentirety.

This application is also related to U.S. patent application Ser. No.12/393,921, filed Feb. 26, 2009; U.S. patent application Ser. No.12/807,278, filed Aug. 31, 2010; U.S. patent application Ser. No.12/876,840, filed Sep. 7, 2010; U.S. Provisional Application No.61/325,155, filed Apr. 16, 2010; U.S. Provisional Application No.61/325,260, filed Apr. 16, 2010; U.S. Provisional Application No.61/247,519, filed Sep. 30, 2009; U.S. Provisional Application No.61/415,174, filed Nov. 18, 2010; and U.S. Provisional Application No.61/422,490, filed Dec. 13, 2010. The disclosures of the above-mentionedapplications are incorporated herein by reference in their entirety.

BACKGROUND

Diabetes Mellitus is an incurable chronic disease in which the body doesnot produce or properly utilize insulin. Insulin is a hormone producedby the pancreas that regulates blood glucose. In particular, when bloodglucose levels rise, e.g., after a meal, insulin lowers the bloodglucose levels by facilitating blood glucose to move from the blood intothe body cells. Thus, when the pancreas does not produce sufficientinsulin (a condition known as Type 1 Diabetes) or does not properlyutilize insulin (a condition known as Type II Diabetes), the bloodglucose remains in the blood resulting in hyperglycemia or abnormallyhigh blood sugar levels.

People suffering from diabetes often experience long-term complications.Some of these complications include blindness, kidney failure, and nervedamage. Additionally, diabetes is a factor in acceleratingcardiovascular diseases such as atherosclerosis (hardening of thearteries), which often leads stroke, coronary heart disease, and otherdiseases, which can be life threatening.

The severity of the complications caused by both persistent high glucoselevels and blood glucose level fluctuations has provided the impetus todevelop diabetes management systems and treatment plans. In this regard,diabetes management plans historically included multiple daily testingof blood glucose levels typically by a finger-stick to draw and testblood. The disadvantage with finger-stick management of diabetes is thatthe user becomes aware of his blood glucose level only when he performsthe finger-stick. Thus, blood glucose trends and blood glucose snapshotsover a period of time is generally unknown. More recently, diabetesmanagement has included the implementation of glucose monitoringsystems. Glucose monitoring systems have the capability to monitor auser's blood glucose levels over a duration of time. Thus, such systemshave the ability to illustrate not only present blood glucose levels buta snapshot of blood glucose levels and blood glucose fluctuations over aperiod of time.

SUMMARY

Aspects of the present disclosure relate to analyte monitoring systems,devices, and methods thereof. On-body units are provided and include atranscutaneous analyte sensor, electronic circuitry electrically coupledto the analyte sensor, and an on-body housing having electrical contactsdisposed thereon. The on-body housing comprises a substantially flatsurface and a curved and convex surface opposite the substantially flatsurface. Systems and methods including the on-body units are alsoprovided.

Aspects of the present disclosure relate to methods for performingcontinuity measurements on on-body units. The methods includepositioning an on-body unit (OBU) on a skin of a subject, contacting acontinuity test instrument to the OBU; and performing a continuitymeasurement with the continuity test instrument.

In certain embodiments, the methods include providing an alternatingcurrent signal to two of the electrical contacts on the on-body housingof the on-body units. In certain embodiments, the methods includeproviding a direct current signal in one direction across two of theelectrical contacts for a specific amount of time, and then providingthe direct current signal in the opposite direction across the same twoelectrical contacts for the same amount of time. In certain embodiments,the methods include performing a continuity measurement on one of theelectrical contacts on the on-body housing. In certain embodiments, themethods include performing a continuity measurement across isolatedelectrical contacts on the on-body housing.

INCORPORATION BY REFERENCE

The following patents, applications and/or publications are incorporatedherein by reference for all purposes: U.S. Pat. No. 7,041,468; U.S. Pat.No. 5,356,786; U.S. Pat. No. 6,175,752; U.S. Pat. No. 6,560,471; U.S.Pat. No. 5,262,035; U.S. Pat. No. 6,881,551; U.S. Pat. No. 6,121,009;U.S. Pat. No. 7,167,818; U.S. Pat. No. 6,270,455; U.S. Pat. No.6,161,095; U.S. Pat. No. 5,918,603; U.S. Pat. No. 6,144,837; U.S. Pat.No. 5,601,435; U.S. Pat. No. 5,822,715; U.S. Pat. No. 5,899,855; U.S.Pat. No. 6,071,391; U.S. Pat. No. 6,120,676; U.S. Pat. No. 6,143,164;U.S. Pat. No. 6,299,757; U.S. Pat. No. 6,338,790; U.S. Pat. No.6,377,894; U.S. Pat. No. 6,600,997; U.S. Pat. No. 6,773,671; U.S. Pat.No. 6,514,460; U.S. Pat. No. 6,592,745; U.S. Pat. No. 5,628,890; U.S.Pat. No. 5,820,551; U.S. Pat. No. 6,736,957; U.S. Pat. No. 4,545,382;U.S. Pat. No. 4,711,245; U.S. Pat. No. 5,509,410; U.S. Pat. No.6,540,891; U.S. Pat. No. 6,730,200; U.S. Pat. No. 6,764,581; U.S. Pat.No. 6,299,757; U.S. Pat. No. 6,461,496; U.S. Pat. No. 6,503,381; U.S.Pat. No. 6,591,125; U.S. Pat. No. 6,616,819; U.S. Pat. No. 6,618,934;U.S. Pat. No. 6,676,816; U.S. Pat. No. 6,749,740; U.S. Pat. No.6,893,545; U.S. Pat. No. 6,942,518; U.S. Pat. No. 6,514,718; U.S. Pat.No. 5,264,014; U.S. Pat. No. 5,262,305; U.S. Pat. No. 5,320,715; U.S.Pat. No. 5,593,852; U.S. Pat. No. 6,746,582; U.S. Pat. No. 6,284,478;U.S. Pat. No. 7,299,082; U.S. Patent Application No. 61/149,639,entitled “Compact On-Body Physiological Monitoring Device and MethodsThereof”, U.S. patent application Ser. No. 11/461,725, filed Aug. 1,2006, entitled “Analyte Sensors and Methods”; U.S. patent applicationSer. No. 12/495,709, filed Jun. 30, 2009, entitled “Extruded ElectrodeStructures and Methods of Using Same”; U.S. patent application Ser. No.12/698,124, filed Feb. 1, 2010, entitled “Compact On-Body PhysiologicalMonitoring Devices and Methods Thereof”; U.S. patent application Ser.No. 12/698,129, filed Feb. 1, 2010, entitled “Analyte Sensor AndApparatus For Insertion Of The Sensor”; U.S. Patent ApplicationPublication No. US2004/0186365; U.S. Patent Application Publication No.2007/0095661; U.S. Patent Application Publication No. 2006/0091006; U.S.Patent Application Publication No. 2006/0025662; U.S. Patent ApplicationPublication No. 2008/0267823; U.S. Patent Application Publication No.2007/0108048; U.S. Patent Application Publication No. 2008/0102441; U.S.Patent Application Publication No. 2008/0066305; U.S. Patent ApplicationPublication No. 2007/0199818; U.S. Patent Application Publication No.2008/0148873; U.S. Patent Application Publication No. 2007/0068807; USpatent Application Publication No. 2010/0198034; U.S. Patent ApplicationPublication No. 2010/0325868; and U.S. provisional application No.61/149,639 titled “Compact On-Body Physiological Monitoring Device andMethods Thereof”, the disclosures of each of which are incorporatedherein by reference in their entirety.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 illustrates an overall system of the analyte monitoring system,according to certain embodiments;

FIG. 2 illustrates the components of an analyte monitoring system,according to certain embodiments;

FIG. 3 illustrates a perspective view of electrical contacts of an onbody housing that are coupleable to corresponding contacts on an analytereader, according to certain embodiments;

FIG. 4 illustrates a circuit diagram of a self-powered on-body unit,according to certain embodiments;

FIGS. 5A and 5B illustrate a perspective view and top view,respectively, of an on-body housing, according to certain embodiments;

FIG. 6A illustrates a perspective view of a dome-shaped on-body housingwith a base perimeter that is flat, according to certain embodiments;

FIG. 6B illustrates a perspective view of a dome-shaped on-body housingwith a base perimeter that is recessed, according to certainembodiments;

FIG. 7 illustrates a perspective view of an on-body housing that iscone-shaped, according to certain embodiments;

FIG. 8 illustrates a perspective view of an on-body housing, accordingto certain embodiments;

FIGS. 9A and 9B illustrate a perspective view and top view,respectively, of an on-body housing having isolated electrical contacts,according to certain embodiments;

FIG. 10A illustrates an on-body housing having two isolated contacts,according to certain embodiments;

FIG. 10B illustrates an on-body housing having two isolated contacts,according to certain embodiments;

FIG. 10C illustrates an on-body housing having two isolated contacts,according to certain embodiments;

FIG. 10D illustrates an on-body housing having two isolated contacts,according to certain embodiments;

FIG. 11 illustrates a flowchart for a method for performing a continuitymeasurement on an on-body unit, according to certain embodiments;

FIG. 12 illustrates a flowchart for a method for performing a continuitymeasurement on an on-body unit, according to certain embodiments;

FIG. 13 illustrates a flowchart for a method for performing a continuitymeasurement on an on-body unit, according to certain embodiments; and

FIG. 14 illustrates a flowchart for a method for performing a continuitymeasurement on an on-body unit, according to certain embodiments.

DETAILED DESCRIPTION

Before the present disclosure is described in additional detail, it isto be understood that this disclosure is not limited to particularembodiments described, as such may, of course, vary. It is also to beunderstood that the terminology used herein is for the purpose ofdescribing particular embodiments only, and is not intended to belimiting, since the scope of the present disclosure will be limited onlyby the appended claims.

Where a range of values is provided, it is understood that eachintervening value, to the tenth of the unit of the lower limit unlessthe context clearly dictates otherwise, between the upper and lowerlimit of that range and any other stated or intervening value in thatstated range, is encompassed within the disclosure. The upper and lowerlimits of these smaller ranges may independently be included in thesmaller ranges is also encompassed within the disclosure, subject to anyspecifically excluded limit in the stated range. Where the stated rangeincludes one or both of the limits, ranges excluding either or both ofthose included limits are also included in the disclosure.

Unless defined otherwise, all technical and scientific terms used hereinhave the same meaning as commonly understood by one of ordinary skill inthe art to which this disclosure belongs. Although any methods andmaterials similar or equivalent to those described herein can also beused in the practice or testing of the present disclosure, the preferredmethods and materials are now described. All publications mentionedherein are incorporated herein by reference to disclose and describe themethods and/or materials in connection with which the publications arecited.

It must be noted that as used herein and in the appended claims, thesingular forms “a”, “an”, and “the” include plural referents unless thecontext clearly dictates otherwise.

The publications discussed herein are provided solely for theirdisclosure prior to the filing date of the present application. Nothingherein is to be construed as an admission that the present disclosure isnot entitled to antedate such publication by virtue of prior disclosure.Further, the dates of publication provided may be different from theactual publication dates which may need to be independently confirmed.

As will be apparent to those of skill in the art upon reading thisdisclosure, each of the individual embodiments described and illustratedherein has discrete components and features which may be readilyseparated from or combined with the features of any of the other severalembodiments without departing from the scope or spirit of the presentdisclosure.

The figures shown herein are not necessarily drawn to scale, with somecomponents and features being exaggerated for clarity.

As summarized, aspects of the present disclosure relate to analytemonitoring systems, devices, and methods thereof. On-body units areprovided and include a transcutaneous analyte sensor, electroniccircuitry electrically coupled to the analyte sensor, and an on-bodyhousing having electrical contacts disposed thereon. The on-body housingcomprises a substantially flat surface and a curved and convex surfaceopposite the substantially flat surface. Systems and methods includingthe on-body units are also provided.

As summarized above, aspects of the present disclosure relate to methodsfor performing continuity measurements on on-body units. The methodsinclude positioning an on-body unit (OBU) on a skin of a subject,contacting a continuity test instrument to the OBU; and performing acontinuity measurement with the continuity test instrument. In certainembodiments, the methods include providing an alternating current signalto two of the electrical contacts on the on-body housing of the on-bodyunits. In certain embodiments, the methods include providing a directcurrent signal in one direction across two of the electrical contactsfor a specific amount of time, and then providing the direct currentsignal in the opposite direction across the same two electrical contactsfor the same amount of time. In certain embodiments, the methods includeperforming a continuity measurement on one of the electrical contacts onthe on-body housing. In certain embodiments, the methods includeperforming a continuity measurement across isolated electrical contactson the on-body housing.

Systems

Aspects of the present disclosure relate to a transcutaneouslypositionable analyte sensor in signal communication with electronicswhich process signals from the analyte sensor transfer or otherwiseprovide the processed signals related to monitored analyte level to areceiver unit, a blood glucose meter or other devices configured toreceive, process, analyze, output, display and/or store the processedsignals. For example, analyte monitoring systems may include in vivoanalyte sensors in fluid contact with body fluid such as interstitialfluid to monitor one or more analyte levels, such as glucose or a ketonebody. Embodiments may include electronics and/or data processing,storage and/or communication components that are electrically coupled tothe analyte sensor, and may include a housing that is placed orpositioned on the body surface such as on the skin surface and adheredthereon with an adhesive and retained and maintained in the adheredposition for the duration of the analyte monitoring time period usingthe analyte sensor such as, for example, about 15 days or more, about 10days or more, about 7 days or more, or about 5 days or more, or about 3days or more. The housing including the electronics and/or dataprocessing, storage and/or data communication components may bepositioned on discrete on-body locations including under clothing duringthe duration of the monitoring time period.

The analyte monitoring device that is coupled to the body and includesthe analyte sensor, housing, and electronic circuitry is also referredto herein as an “on-body unit”, “OBU”, “on body patch”, and “patch”. Insome instances, the analyte monitoring device as a whole maycollectively be referred to as a “sensor” or “analyte sensor” or“self-powered sensor”.

In some embodiments, the housing of the on body patch or housing of theelectronics is water proof such that the user or the patient wearing thehousing on a discrete on-body location may swim, shower, exercise orotherwise engage in daily activities with comfort and withoutinconvenience. Certain embodiments include the adhesive provided on thebottom surface of the housing in contact with the skin surface thatretains the housing in position on the skin surface during the durationof the analyte monitoring time period discussed above. The on-bodyhousing may be made from any variety of materials, including metals,metal alloys, polymers (e.g., plastics, rubber, etc.), combinationthereof, etc.

In some aspects of the present disclosure, the OBU includes electricalcontacts on the surface of the housing that includes the electronicsand/or data processing, storage and/or communication components whichare electrically coupled to the analyte sensor. When electrical contactsor probes provided on a reader unit is in physical contact with thecorresponding electrical contacts on the surface of the housing thatincludes the electronics and/or data processing, storage and/orcommunication components, signals associated with the monitored analytelevel by the OBU are acquired by the reader. The reader unit may also bereferred to herein as “receiver unit”. As described above, the readerunit may be an analyte monitoring device that is brought in contact withthe OBU to acquire readings from the OBU. The reader may be, forexample, an analyte meter (e.g., blood glucose meter), a mobile devicethat has been adapted to receive readings from the OBU, etc. Additionaldetails regarding analyte data acquisition by physically contacting ortouching the housing of sensor electronics with a reader (e.g., bloodglucose meter) is provided in U.S. Provisional Application No.61/247,519, the disclosure of which is incorporated herein by referencefor all purposes. In this manner, embodiments of the present disclosureinclude analyte data acquisition or ability to obtain real time glucosedata by physically touching or contacting the reader unit to the housingof the electronics and/or data processing, storage and/or communicationcomponents.

In some aspects of the present disclosure, the OBU is self-powered suchthat an external power source such as a battery is unnecessary to havethe OBU generate a signal that is proportional to the monitored analyteconcentration. In some instances, the OBU may include one or more powersources such as a battery, but is self-powered to the extent that achemical reaction from the in-vivo analyte sensor provides necessarycurrent to the electronics of the OBU for proper operation. Theself-powered OBU may also be referred to herein generally as a“self-powered sensor”. Additional details of self-powered sensors areprovided in U.S. patent application Ser. No. 12/393,921 filed Feb. 26,2009, the disclosure of which is incorporated herein by reference forall purposes. The absence of the external power source such as a battery(or the reduction in size of the external power source required)provides embodiments of the present disclosure with the size and/or theform factor of the housing for the electronics and/or data processing,storage and/or communication components to be small (for example,approximately the size of a dime—about 18 mm in diameter) that iscomfortable to wear on the skin surface during the approximately 10 daysof wear on the skin surface.

In some aspects of the present disclosure, real time analyte dataacquisition is provided by physical contact between the reader unit andthe housing of the OBU. Signals are provided to the reader unit that areassociated with the real time analyte concentration (such as the realtime glucose value) and/or monitored analyte concentration trendinformation for a predetermined time period (such as for example, thepast 3 hours of glucose concentration that are monitored by the analytesensor and stored by the electronics and/or data processing, storageand/or communication components in the housing). In some aspects, trendinformation may be stored and/or provided with the real time monitoredanalyte concentration where the predetermined time period may be about 1hour, about 2 hours, about 5 hours or more.

FIG. 1 illustrates an overall system of the analyte monitoring systemincluding real time data acquisition related to embodiments of thepresent disclosure. Referring to FIG. 1, analyte monitoring system 100is shown and comprises on-body housing 110 that is positioned or adheredto the skin surface 120 of the user or the patient using, for example,an adhesive 131 to retain the position of the on-body housing 110 on theskin surface during the monitoring time period such as, for example,about 10 days or more. Referring to FIG. 1, as shown, when the user orthe patient wishes to determine the analyte concentration, the reader(e.g., blood glucose meter) 140 is positioned such that it contacts ortouches the on-body housing 110 as shown. In certain embodiments, thephysical contact or touching of the on-body housing 110 with the reader140 transfers one or more signals from the electronics contained withinthe on-body housing 110 to the reader 140 via electrical communication.The transferred or provided signals may include signals corresponding tothe real time analyte concentration level such as, for example, realtime glucose level information, monitored analyte concentration trendinformation such as, for example but not limited to, the previous threehours, the rate of change of the analyte concentration determined basedat least in part of the monitored analyte concentration trendinformation, or one or more combinations thereof.

Referring again to FIG. 1, it can be seen from the middle insert figurethat an in-vivo analyte sensor 150 may be transcutaneously positionedsuch that a portion of the analyte sensor is positioned and retainedunder the skin layer during the monitoring time period of approximately,for example, but not limited to ten days, and further, that the in-vivoanalyte sensor 150 is coupled to the on-body housing 110 such that theelectrodes (working and counter electrodes, for example) of the in-vivoanalyte sensor 150 are electrically coupled to one or more electricalcomponents in the on-body housing 110 and configured to process andstore, among others, the signals from the in-vivo analyte sensor 150.Furthermore, by way of nonlimiting comparison, as discussed above,embodiments including self-powered analyte sensor which in someembodiments does not need an external power supply and the touch basedanalyte data acquisition/communication with obviates the need for awireless data communication component, permits the sizing of the on-bodyhousing 110 to be approximately the size of a dime. After the monitoringtime period, the in-vivo analyte sensor 150 and/or on-body housing 110may be removed, disposed, and replaced.

FIG. 2 illustrates an exploded perspective view of the components ofanother exemplary analyte monitoring system, in accordance with certainembodiments of the present disclosure. Referring to FIG. 2, as shown,embodiments include a reader 240 that is provided with probes 211 a, 211b, 211 c configured to make electrical contact with the respective oneof the concentric electrical contacts 220 on the on-body housing 210connected to an in-vivo analyte sensor 250. As can be seen, embodimentsinclude the probes 211 a, 211 b, 211 c at a predetermined position onthe housing of the reader 240, and at a position relative to each othersuch that when the reader 240 is positioned in contact with the on-bodyhousing 210, each of the probes 211 a, 211 b, 211 c of the reader 240makes physical contact with the respective one of the concentricelectrical contacts 220 on the on-body housing 210.

The in-vivo analyte sensor 250 extends from the on-body housing 210 totranscutaneously position electrodes (e.g., working and counterelectrodes) on the in-vivo analyte sensor 250 under the skin layer of auser. The electrodes of the in-vivo analyte sensor 250 are electricallycoupled to one or more electrical components or sensor electronics inthe on-body housing 210. Such electronics are configured to process andstore the signals from the in-vivo analyte sensor 250. After themonitoring time period, the in-vivo analyte sensor 250 and/or on-bodyhousing 210 may be removed, disposed, and replaced.

Referring to FIG. 2, while embodiments include concentric electricalcontacts configuration on the on-body housing 210, in accordance withthe embodiments of the present disclosure, the electrical contacts mayinclude other shapes and sizes such as spaced apart probes, contactpads, oval shaped contacts, and any other suitable configuration toeasily establish the electrical contact with the respective of theprobes 211 a, 211 b, 211 c on the in-vivo 240 when the in-vivo 240 isbrought into contact with the on-body housing 210.

FIG. 3 illustrates a perspective view of on-body housing electricalcontacts coupleable to the electrode contacts on the reader, inaccordance with some embodiments of the present disclosure. Referring toFIG. 3, the reader includes a plurality of mating or contact sites 311a, 311 b, 311 c, 311 d, 311 e, where each of the plurality of contactsites 311 a, 311 b, 311 c, 311 d, 311 e include probes to establishelectrical contact with the corresponding one of the concentricelectrical contacts 320 on the on-body housing 310. That is, in certainembodiments, to facilitate alignment of the probes of the receiver unitor the blood glucose meter to the concentric electrical contacts 320 ofthe on-body housing 310, the receiver unit or the blood glucose metermay be provided with multiple contact sites 311 a, 311 b, 311 c, 311 d,311 e such that any one of the five contact sites 311 a, 311 b, 311 c,311 d, 311 e shown in FIG. 3 may transfer the signals generated from thein-vivo analyte sensor to the reader.

In certain instances, the plurality of contact sites 311 a, 311 b, 311c, 311 d, 311 e may be provided on an outer housing surface of thereader, where each of the plurality of contact sites 311 a, 311 b, 311c, 311 d, 311 e are beveled or include a groove so as to facilitate themating with the respective concentric electrical contacts on the on-bodyhousing. In some instances, geometries and/or configurations of themating sites on the reader or the on-body housing may facilitate and/oraid the physical connection between the two components during analytesensor data acquisition to determine real time analyte concentrationlevel and/or trend information. For example, each contact site 311 a,311 b, 311 c, 311 d, 311 e of the reader may include a rail orprotrusion that aligns with a corresponding respective groove on theon-body housing 310 to guide, aid, and/or facilitate the alignment orproper positioning of the contact probes on the reader to the respectiveconcentric electrical contacts on the on-body housing 310. Such a grooveon the on body housing 310 in certain embodiments may minimizeinterference and/or discomfort while wearing the on-body housing on theskin surface during the monitoring time period of for example, about tendays.

FIG. 4 illustrates a circuit diagram of a self-powered OBU, according tocertain embodiments. As shown, the electronics within the OBU includestwo resistor-capacitor (RC) pairs 610 and 620 that are provided inseries. RC pair 620 is shown comprising R1 in parallel with C1. RC pair610 is shown comprising R2 in parallel with C1. In the example shown,resistor R1 is approximately 5 MΩ and capacitor C1 is approximately 10μF; and resistor R2 is approximately 5 MΩ and capacitor C2 isapproximately 94 μF. The embodiment shown includes approximateresistance values of resistors R1 and R2 at room temperature(approximately 25° C.). Some embodiments include such relatively highresistance values to increase the voltage signal across the working andcounter electrodes of the in-vivo analyte sensor. It should beappreciated that the values shown are exemplary and that other valuesmay be implemented in other embodiments. For example, C2 may be providedby one or more capacitors, and R1,R2 may be implemented as resistors orthermistors.

Node A is shown at one end of the first RC pair; node B between the twoRC pairs; and node C at the other end of the second RC pair. Currentsource 605 is shown across nodes A and C and represents the current flowprovided to circuit 600 by the in-vivo analyte sensor when contactinginterstitial fluid under a skin layer.

The working electrode of the in-vivo analyte sensor is electricallyconnected to node A, and the counter electrode of the in-vivo analytesensor is electrically connected to node C. When the in-vivo sensorcontacts interstitial fluid, for example, current flow is generated fromthe resulting chemical reaction that takes place. For example, currentwithin the nanoamp (nA) range may be generated and provided to the RCpairs of the electronic circuit.

Concentric electrical contacts (not shown) are disposed externally onthe housing of the OBU (e.g., as shown in FIGS. 5A and 5B) and are eachcoupled to a respective node A, B, and C in the electronic circuit shownin FIG. 4. In this way, one concentric electrical contact is provided atthe working electrode (node A), another concentric electrical contact atthe counter electrode (node C), and yet another concentric electricalcontact between the two RC pairs (node B).

The circuit shown enables measurements to be taken that are indicativeof analyte concentrations detected by the in-vivo analyte sensor. Vab isthe voltage across the first RC pair (e.g., across nodes A and B) andreflects the current glucose measurement, as filtered based on the R1*C1time constant. Vbc is the voltage across the second RC pair (e.g.,across nodes B and C) and reflects the average glucose value over alonger period of time, as determined by the R2*C2 time constant.Furthermore, the difference between the two voltage readings Vab and Vbcrepresents trend information for the detected analyte concentrations.

OBUs and On-Body Housings

In some aspects of the present disclosure, voltage measurements from theOBU may be acquired by an analyte reader (e.g., a blood glucose meter)that is brought into physical contact with the OBU. Electrical contactson the reader contact the concentric electrical contacts on the OBU andenable the appropriate measurements to be communicated to the reader.Having good electrical contact between the reader and the OBU isimportant in ensuring accurate readings are obtained. For example,accumulation of water or liquids on the housing of the OBU can lead tofaulty readings by providing a conductive parallel path to R1 and/or R2which alters the corresponding voltage measurement.

The on-body housing includes a substantially flat surface and a curvedand convex surface that is opposite of the substantially flat surface.The substantially flat surface may include adhesive, for example, thatis used to apply the OBU to the surface of a body part. Thesubstantially flat surface contacts and sticks to the skin surface,while the curved and convex surface extends outward away from thesubstantially flat surface and skin surface. The substantially flatsurface is thus sometimes referred to herein as the “bottom surface” andthe curved and convex surface sometimes referred to herein as the “topsurface”.

The top surface of the on-body housing includes the concentricelectrical contacts that contact the reader when the reader is broughtinto contact with the top surface of the housing. The term “top surface”is used herein to refer generally to the surface of the housing that isopposite the substantially flat surface and skin surface (when the OBUis attached to the skin).

The surface contour of the top surface of the on-body housing can affectthe amount of accumulation of water or other fluids on the housing, andthus affect the adequacy of the electrical contact between the OBU andthe reader. For instance, an on-body housing with a flat or level topsurface enables water or other liquids to accumulate on the top surfaceof the housing, increasing the likelihood of a false reading.Furthermore, liquids may accumulate in OBU housings having top surfacecontours that include recessed, depressed, or concave top surfacecontours. Furthermore, a top surface that is generally concave wouldextend generally inward towards the substantially flat surface of theon-body housing (or towards the body part when the OBU is attached to abody part). The concave contour would form depositories on the topsurface for liquid to collect and create conductive parallel paths whichwould corrupt readings.

In certain aspects of the present disclosure, the OBU includes anon-body housing that has a substantially flat surface and a curved andconvex surface that is opposite of the substantially flat surface. The“convex” surface extends generally outward away from the substantiallyflat surface and skin surface (when the OBU is attached to the bodypart). In this way, the OBU is adapted to have a surface contour that isconducive to avoiding accumulation of water or other liquids that couldinterfere with the measurements. The surface contour of the housing issuch that the water or other liquids tend not to pool or otherwisecollect on the top surface of the housing.

In certain embodiments, the OBU includes a housing that is dome-shaped.The dome-shaped housing includes a top surface that is curved andconvex. It should be appreciated that the dome-shaped housing maycomprise a top surface having a variety of shapes—e.g., spherical,ellipsoidal, or any other curved and convex surface contour. It shouldalso be appreciated that a curved surface contour that is referred to asspherical and/or ellipsoidal does not necessarily require that thecontour be a complete sphere or ellipsoid, but rather may be part of asphere or ellipsoid. For example, the contour may be a semi-spherical,quarter-spherical, or other fractional piece of a sphere. The sameapplies to other surface contours such as ellipsoids.

It should also be appreciated that the shapes of the surface contoursdescribed above are not required to be exact, but rather may besubstantially or approximately the shape that is described. For example,a surface that is referred to as spherical shaped also includes surfacesthat are substantially spherical or approximately spherical.

It should also be appreciated that the curved and convex surfaceincludes contours in two dimensions that may each be independentlycircular, elliptical, oval, or otherwise curved and convex. For example,an ellipsoidal surface contour may include a circular contour viewedfrom one direction and an elliptical contour viewed from anotherdirection.

The substantially flat base of the on-body housing may also vary inshape. In some embodiments, the substantially flat base is circular. Inother embodiments, the substantial flat base is elliptically shaped. Inyet other embodiments, the substantially flat base is another regular orirregular shape.

FIGS. 5A and 5B illustrate a perspective view and top view,respectively, of an on-body housing of an OBU, according to someembodiments. In the embodiment shown, the on-body housing 310 isdome-shaped. The top surface 345 of the housing 310 is curved andconvex. It should be appreciated that the curvature may vary indifferent embodiments. For example, the surface contour of the topsurface 345 of the housing 310 may have circular, elliptical, parabolic,or other curved contours that do not provide a flat or concave topsurface that may accumulate water or other liquid on the top surface ofthe OBU.

On-body housing includes electrical contacts 321, 322, and 323 disposedon the top surface of the housing. In the embodiment shown, theelectrical contacts are concentric electrical contacts that are disposedexternally at different heights (H) on the top surface of the on-bodyhousing. Concentric electrical contacts 321, 322, and 323 are disposedon the external side of the on-body housing 310 that contacts the reader(not shown). Concentric electrical contact 322 is disposed on theon-body housing 310 concentrically around concentric electrical contact323. Concentric electrical contact 321 is disposed on the on-bodyhousing concentrically around concentric electrical contact 322. In theembodiment shown, the concentric electrical contacts 321, 322, and 323are each ring-shaped and disposed on a dome-shaped on-body housing 310with the center of the rings aligned with a center 324 of the on-bodyhousing 310. It should be appreciated that the concentric electricalcontacts 321, 322, and 323 may be approximately centered with respect tothe center of the housing.

A height axis H is shown in FIG. 5A for reference purposes. Concentricelectrical contact 321 is shown at a height H1; concentric electricalcontact 322 is shown at a height H2; concentric electrical contact 323is shown at a height H3; and the center 324 of the on-body housing 310is shown at a height H4. It should be appreciated that the height ofeach concentric electrical contact 321, 322, and 323 on the on-bodyhousing 310 may vary. In some embodiments, the concentric electricalcontacts are equidistantly spaced in height—e.g., the distance betweenH1 and H2 is equal to the distance between H2 and H3. In someembodiments, the concentric electrical contacts 321, 322, and 323 arenot equidistantly spaced in height.

As shown in FIG. 5B, concentric electrical contact 323 is shown adistance D3 from center 324; concentric electrical contact 322 is showna distance D2 from concentric electrical contact 323; and concentricelectrical contact 321 is shown a distance D1 from concentric electricalcontact 322. In some embodiments, these distances of the concentricelectrical contacts are equidistantly spaced—e.g., the distance betweenD1 and D2 is equal to the distance between D2 and D3. In otherembodiments, these distances of the concentric electrical contacts arenot equidistantly spaced.

As shown in FIGS. 5A and 5B, the top surface 345 of the housing iscurved and convex such that any water or liquid on the housing will notaccumulate on the top surface and create conductive parallel paths whichalter readings. As concentric electrical contacts 321, 322, and 323 aredisposed on the curved and convex top surface, water or other fluidaccumulation is minimized or avoided between the electrical contacts321, 322, and 323.

It should be appreciated that in some alternative embodiments,concentric electrical contact 323 may be a solid circular shape insteadof ring-shaped. For example, concentric electrical contacts 322 and 321may be concentrically disposed around concentric electrical contact 323.

In certain embodiments, the base perimeter of the housing comprises aflat edge. For example, FIG. 6A illustrates a perspective view of adome-shaped on-body housing with a base perimeter that has flat edge,according to certain embodiments. As shown, housing 310 includes curvedand convex surface 345 and concentric electrical contacts 321, 322, and323 disposed thereon. As shown, the base perimeter of the housing 310includes a flat edge 350.

In other embodiments, the base perimeter of the housing is recessedinward—e.g., decreases in width (e.g., decreasing in cross-sectionaldiameter when viewed from the top). For example, FIG. 6B illustrates aperspective view of a dome-shaped on-body housing with a recessed baseperimeter, according to certain embodiments. As shown, housing 310includes curved and convex surface 345 and concentric electricalcontacts 321, 322, and 323 disposed thereon. As shown, the housing 310includes a recessed base perimeter 355.

In certain embodiments, the housing is cone-shaped. The cone-shapedhousing may include any variety of cone shapes—e.g., standard conical,bi-conical, power series (also known as parabolic), etc. For example,FIG. 7 illustrates a perspective view of an on-body housing that iscone-shaped, according to certain embodiments. In the embodiment shown,concentric electrical contacts 321, 322, and 323 are disposed externallyon the top surface 345 of the on-body housing 310 that contacts thereader (not shown). Concentric electrical contact 322 is disposed on theon-body housing 310 concentrically around concentric electrical contact323. Concentric electrical contact 321 is disposed on the on-bodyhousing concentrically around concentric electrical contact 322. In theembodiment shown, the concentric electrical contacts 321, 322, and 323are each ring-shaped and disposed on the top surface 345 of the housingwith the center of the rings aligned with a center 324 of the on-bodyhousing 310. In some alternative embodiments, the housing 310 mayinclude a base perimeter with a flat edge or recessed base perimeter, asdescribed above.

It should be appreciated that the above described embodiments areexemplary and that other shape of the housing may be implemented inalternative embodiments. The shape of the top surface of the housingshould prevent water or other liquids from pooling or otherwisecollecting on the exterior of the housing—e.g., within recesses orcontainers formed by the contour of housing.

For example, FIG. 8 illustrates a perspective view of an on-bodyhousing, according to certain embodiments. In the embodiment shown,housing 310 includes a top surface 345 that is curved and convex. Whiletop surface 345 includes portions of the contour that are curvingupwards, the surface 345 as a whole is convex and extends generallyoutward from the substantially flat base without any recesses,depressions, or concave portions that form depositories in which fluidmay accumulate on the top surface of the housing.

Concentric electrical contacts 321, 322, and 323 are disposed externallyon the top surface of the on-body housing 310 that contacts the reader(not shown). Concentric electrical contact 322 is disposed on theon-body housing 310 concentrically around concentric electrical contact323. Concentric electrical contact 321 is disposed on the on-bodyhousing concentrically around concentric electrical contact 322. In theembodiment shown, the concentric electrical contacts 321, 322, and 323are each ring-shaped and disposed on a dome-shaped on-body housing withthe center of the rings aligned with a center 324 of the on-body housing310. As the concentric electrical contacts 321, 322, and 323 aredisposed on a curved and convex surface of the housing 310, water orother fluids are prevented from accumulating such that a parallelconductive path would form. In some alternative embodiments, the housing310 may include a base perimeter with a flat edge or recessed, asdescribed above.

It should be appreciated that in some alternative embodiments,concentric electrical contact 323 may be a solid circular shape insteadof ring-shaped. For example, concentric electrical contacts 322 and 321may be concentrically disposed around concentric electrical contact 323.

Testing for Sufficient Contact with an OBU

In some aspects of the present disclosure, methods and techniques forverifying adequate electrical contact with an OBU, such as onesdescribed herein, are provided. Achieving good electrical contactbetween the on-body housing and the reader (e.g., glucose meter or otheranalyte meter) enables successful measurement readings to be obtained.As previously stated, the mechanical design of the OBU and the readermay increase the robustness of the electrical contacts. In someinstances, electrical continuity tests may be performed to ensure thatthe reader is making good electrical contact with the OBU. Whilecontinuity tests may be made using the concentric electrical contacts321, 322, and 323, the continuity measurement may potentially corruptthe voltage across one or both RC pairs 610,620. This can occur becausecontinuity measurements may involve injecting a current across one orboth of the resistors, thereby changing the voltage across one or bothRC pairs 610,620.

In some aspects of the present disclosure, one or more isolated contactsmay be disposed externally on the on-body housing and used to performcontinuity measurements. The isolated contacts are different from theconcentric electrical contacts 321, 322, and 323 and are isolated fromboth of the RC pairs. The quantity, shape, and location of the isolatedcontacts on the top surface of the on-body housing may vary—e.g., asdemonstrated in FIGS. 9 and 10.

FIGS. 9A and 9B illustrate a perspective view and top view of an on-bodyhousing of an OBU, according to some embodiments. In the embodimentshown, the concentric electrical contacts 321, 322, and 323 are disposedexternally on on-body housing 310. Concentric electrical contacts 321,322, and 323 are disposed on the top surface of the on-body housing 310with concentric electrical contact 321 disposed around concentricelectrical contact 322, which is disposed around concentric electricalcontact 323. Again, concentric electrical contacts 321, 322, and 323 arering-shaped and disposed on a dome-shaped on-body housing with thecenter of the rings aligned with a center 324 of the on-body housing310.

The embodiment shown in FIGS. 9A and 9B differ from the embodiment shownin FIGS. 5A and 5B by having a set of isolated contacts 705 disposedexternally on the on-body housing 310. The set of isolated contacts 705is separate from the concentric electrical contacts 321, 322, and 323and isolated from both RC pairs 610,620 (shown in FIG. 4). The set ofisolated contacts 705 contact the corresponding contact elementsdisposed on the reader and enable a continuity test to be performed viathe isolated contacts 705. As the isolated contacts 705 are isolatedfrom the concentric electrical contacts 321, 322, and 323 and isolatedfrom both RC pairs 610,620, any current provided by the continuity testdoes not disturb or corrupt the voltage signals across the concentricelectrical contacts 321, 322, and 323, and thus does not alter thevoltages across one or both RC pairs 610,620.

In the embodiment shown, the set of isolated contacts 705 are disposedon the on-body housing 310 with the concentric electrical contacts 323.It should be appreciated that the set of isolated contacts 705 maycomprise a plurality of contacts positioned in any variety ofarrangements. FIGS. 10A-10D illustrate top views of an OBU with a set ofisolated contacts, according to certain embodiments. As shown, OBUcomprises an on-body housing 310; concentric electrical contacts 321,322, and 323; and a set of isolated contacts 705. The set of isolatedcontacts 705 are shown comprising isolated contacts 705A and 705B. Itshould be appreciated that a different number of isolated contacts otherthan two may be implemented in other embodiments.

In FIG. 10A, both isolated contacts 705A and 705B are concentricelectrical contacts that are disposed externally on the top surface 345of the on-body housing 310 within concentric electrical contact 323. Putanother way, isolated contacts 705A and 705B are disposed within allthree concentric electrical contacts 321, 322, and 323. Both isolatedcontacts 705A and 705B are ring-shaped and centered with respect to thecenter of the on-body housing 310.

In FIG. 10B, both isolated contacts 705A and 705B are concentricelectrical contacts that are disposed externally on the top surface 345of the on-body housing 310. Isolated contact 705A is a solid circularelectrical contact disposed within the innermost concentric electricalcontact 323, and isolated contact 705B is a ring-shaped electricalcontact that is concentrically disposed around the three concentricelectrical contacts 321, 322, and 323. Thus, the three real signals onthe three concentric electrical contacts 321, 322, and 323 are disposedbetween the pair of isolated contacts 705A and 705B. In this way, ifthere is continuity between the isolated contacts 705A and 705B, thenthe reader is correctly positioned on the OBU and the reader connectionis in correct alignment for proper contact with the three concentricelectrical contacts 321, 322, and 323 disposed between the pair ofisolated contacts 705A and 705B. It should be appreciated that theconfiguration of having the concentric electrical contacts 321, 322, and323 disposed between the pair of isolated contacts 705A and 705B mayalso apply to the other embodiments (e.g., the embodiments shown FIGS.10A, 10C, and 10D, and variations thereof).

In FIG. 10C, both isolated contacts 705A and 705B are concentricelectrical contacts that are disposed externally on the top surface 345of the on-body housing 310 outside concentric electrical contact 323.Both isolated contacts 705A and 705B are ring-shaped and centered withrespect to the center of the on-body housing 310. In the embodimentshown, both isolated contacts 705A and 705B are disposed outsideconcentric electrical contact 321.

In FIG. 10D, both isolated contacts 705A and 705B are solid circularelectrical contacts that are disposed externally on the top surface 345of the on-body housing 310 within concentric electrical contact 323.Isolated contact 705A is centered with respect to the center of theon-body housing, and isolated contact 705B is not.

It should be appreciated that the shape and position of thecorresponding contacts on the reader may vary but should enableappropriate contact with the arrangement of isolated contacts 705 whenthe reader is brought in contact with the OBU. For example, in someembodiments, the reader includes concentric electrical contacts thatline up with the electrical contacts on the OBU. It should beappreciated that the embodiments shown enable the reader to be placed onthe OBU irrespective of orientation and still permit contact with theelectrical contacts on the OBU. For example, the reader may includering-shaped concentric electrical contacts with the same diameter as thecorresponding electrical contacts on the OBU. Or as another example, thereader may include electrical contacts that are not ring shaped butdisposed at the appropriate distance from center to come in contact withthe corresponding concentric electrical contacts on the OBU. It is notedthat in FIG. 10D, the OBU and reader may still be brought in contactirrespective of orientations—e.g., if the reader includes a concentricelectrical contact that has a diameter that aligns with isolated contact705B. it should also be appreciated that the reader may include aninterface that is designed to physically mate with or “fit” with the OBUto further promote a good electrical connection.

FIG. 11 illustrates flowchart for performing a continuity measurement onan OBU, according to certain embodiments. In block 1105, an OBU havingisolated contacts is provided. For example, the on-body housings 310described in FIGS. 9A-9B and FIGS. 10A-10D may be provided forperforming a continuity measurement. The OBU may, in some instances,already be attached to a body part. In other instances, the OBU may beunattached to a body part during continuity testing. In block 1110, acontinuity measurement is performed using the isolated contacts. Asstated above, the set of isolated contacts contact the correspondingcontact elements disposed on the reader and enable a continuity test tobe performed via the isolated contacts 705. As the isolated contacts 705are isolated from the concentric electrical contacts 321, 322, and 323(or other type of electrical contacts coupled to nodes A, B, and C inFIG. 4), any current provided by the continuity test does not disturb orcorrupt the voltage signals across the RC pairs 610 and 620.

In certain aspects of the present disclosure, a continuity test isperformed across only one of concentric electrical contacts 321, 322, or323. In this way, test current is not injected across one or bothcapacitors, resulting in altered voltages across the capacitors and thusin accurate readings. For example, the reader may be adapted to includetest contacts that contact one of the concentric electrical contacts321, 322, and 323 when the reader and OBU are brought together for atest. If, for instance, a complete circuit is established by theconcentric electrical contact, then sufficient contact is achieved andindicated to the user. If, however, a completed circuit is notestablished, then the insufficient contact is indicated to the user. Asthe single concentric electrical contact provides a short circuit tocomplete the circuit.

FIG. 12 illustrates a flowchart for performing a continuity measurementon a single electrical contact on the OBU, according to certainembodiments. In block 1105, an OBU is provided. For example, the OBU mayinclude concentric electrical contacts disposed on an on-body housingsuch as shown in FIGS. 5-8. In block 1110 a continuity measurement isperformed on one of the concentric electrical contacts 321, 322, and 323electrically connected to nodes A, B, and C in FIG. 4. The continuitymeasurement is performed on the single electrical contact and does notdisturb or corrupt the voltage signals across either of the RC pairs 610and 620.

It should be appreciated that, in some instances, the continuitymeasurement as described in FIG. 12 may be performed on an OBU havingisolated contacts 705. Such continuity measurement may be performed oneither the isolated contacts and/or the concentric electrical contacts321, 322, and 323 (electrically coupled to nodes A, B, and C in FIG. 4).

As stated earlier, continuity measurements can corrupt the voltagesignals Vab and Vbc, as represented in FIG. 4. Continuity measurementsinvolve injecting current (I) into the path under test for a period oftime (T), and the capacitors C1 and C2 in the circuit will accumulatecharge (Q) based on the equation: Q=IT. Thus, the voltages across thecapacitors C1 and C2 are altered by the injected current. Furthermore,the injected current that tests for continuity may be on the order ofmicroamps as compared to nanoamps generated by the self powered OBU,thus significantly affecting the voltage signals Vab and Vbc.

In certain aspects of the present disclosure, an alternating current(AC) signal is provided to perform the continuity measurement usingelectrical contacts electrically connected to nodes A, B, and C in FIG.4 (e.g., concentric electrical contacts 321, 322, and 323). FIG. 13illustrates a flowchart for performing a continuity measurement on anOBU with an AC signal, according to certain embodiments. As shown byblock 1305 an OBU, such as one described herein, is provided. The OBUmay be coupled to a body part in some instances, or not coupled to abody part in other instances. As shown in block 1310, a continuitymeasurement is then performed on the OBU using an AC signal. Forexample, an analyte meter may be configured to couple to the OBU andperform the continuity measurement automatically or as initiated by theuser.

In certain embodiments, the AC signal is a sine wave current that isapplied for one or more full cycles. Any current flowing in onedirection is offset by the equal amount of current flowing in theopposite direction, thus resulting in no net energy residing in the OBU(e.g., no net charge accumulation in the capacitors C1 or C2). Thecontinuity measurement thus does not affect the voltage signals Vab andVbc. It should be appreciated that in other embodiments, the AC signalmay be implemented as another waveform than a sine wave—e.g., squarewave, triangle wave, etc.

In certain aspects of the present disclosure, a DC current pulse is usedto perform the continuity measurement using electrical contactselectrically connected to nodes A, B, and C in FIG. 4 (e.g., concentricelectrical contacts 321, 322, and 323). The DC current pulse is appliedacross two of the electrical contacts in one direction for a period oftime (t). A DC current pulse of the same value as the first is thenapplied across the same two electrical contacts in the oppositedirection for the same period of time (t). In this way, no net energyresides in the OBU (e.g., no net charge accumulation in C1 or C2), andthe signal of interest (e.g., glucose signal) is not altered orperturbed. Moreover, using a small pulse decreases any negativeinfluence by the continuity measurement. For example, because charge isequal to the product of current and time, the smaller the duration ofthe current (e.g., a small pulse), the smaller the charge accumulated.

FIG. 14 illustrates a flowchart for performing a continuity measurementon an OBU, according to certain embodiments. As shown by block 1405 anOBU, such as one described herein, is provided. The OBU may be coupledto a body part in some instances, or not coupled to a body part in otherinstances. As shown in block 1310, a continuity measurement is thenperformed on the OBU using the DC pulse signals described above. Forexample, the reader may be configured to couple to the OBU and performthe continuity measurement automatically or as initiated by the user.For instance, the DC current pulse may be provided in one directionacross two of the concentric electrical contacts 321, 322, and 323 for apredetermined amount of time Immediately thereafter, and withoutrequiring the reader to be moved, another DC current pulse of the samevalue and duration is provided in the opposite direction across the sametwo concentric electrical contacts. In this way, no net energy residesin the OBU (e.g., no net charge accumulation in C1 or C2), and thesignal of interest (e.g., glucose signal) is not altered or perturbed.

In some instances, the measurement accuracy of analyte sensors isdependent upon temperature. As such, in some embodiments, a temperaturesensor is provided with the OBU to measure body temperature at or nearthe analyte sensor. The temperature reading can then be used tocalibrate the measurement readings accordingly. The temperature sensormay be internal or external to the on-body housing. The temperaturesensor may also sit above the skin, or be provided as an electroderunning along the analyte sensor to be transcutaneously implanted belowthe skin. The temperature sensor electrode would then be electricallycoupled to a temperature measurement circuit within the on-body housing.The temperature measurements may be transmitted to the blood glucosemeter upon request. For manufacturability and cost-effectiveness,particularly when the on-body housing is intended to be disposable, itmay be desirable to avoid the inclusion of a temperature sensor and/orcontrol circuitry in the on-body housing. As such, in one embodiment,there is provided reader (e.g., a blood glucose meter, or otherhand-held measurement or analysis instrument) with a temperaturemeasurement sensor and control system. The temperature measurementsensor may be provided on the permanent hand-held instrument to avoiddisposing of the temperature measurement components when the on-bodyhousing is disposed. In some embodiments, a metal bridge may be disposedon the OBU to test for continuity and to measure temperature. Additionaldetails regarding metal bridges that may be implemented on the OBU maybe found in U.S. Pat. No. 5,711,607, issued Jan. 27, 1998, the entiretyof which is incorporated herein by reference.

Analytes that may be monitored include, but are not limited to, acetylcholine, amylase, bilirubin, cholesterol, chorionic gonadotropin,creatine kinase (e.g., CK-MB), creatine, creatinine, DNA, fructosamine,glucose, glutamine, growth hormones, hormones, ketone bodies, lactate,peroxide, prostate-specific antigen, prothrombin, RNA, thyroidstimulating hormone, and troponin. The concentration of drugs, such as,for example, antibiotics (e.g., gentamicin, vancomycin, and the like),digitoxin, digoxin, drugs of abuse, theophylline, and warfarin, may alsobe monitored. In those embodiments that monitor more than one analyte,the analytes may be monitored at the same or different times. In oneembodiment, the analyte sensor is a glucose sensor. In anotherembodiment, the analyte sensor is a ketone sensor.

Various other modifications and alterations in the structure and methodof operation of this disclosure will be apparent to those skilled in theart without departing from the scope and spirit of the embodiments ofthe present disclosure. Although the present disclosure has beendescribed in connection with particular embodiments, it should beunderstood that the present disclosure as claimed should not be undulylimited to such particular embodiments. It is intended that thefollowing claims define the scope of the present disclosure and thatstructures and methods within the scope of these claims and theirequivalents be covered thereby.

What is claimed is:
 1. An analyte monitoring system, comprising: anon-body unit (OBU) for analyte monitoring, the OBU comprising: atranscutaneous analyte sensor; electronic circuitry coupled to theanalyte sensor; and an on-body housing comprising a substantially flatsurface and a curved and convex surface opposite the substantially flatsurface, wherein the on-body housing has electrical contacts disposed onthe curved and convex surface, the electrical contacts electricallycoupled to the electronic circuitry; and a hand-held reader comprising aplurality of electrical contacts that electrically couple to theelectrical contacts on the on-body housing when the reader is positionedin physical contact with the on-body housing.
 2. The analyte monitoringsystem of claim 1, wherein the on-body housing is dome-shaped.
 3. Theanalyte monitoring system of claim 2, wherein the electronic circuitrycomprises first and second RC pairs in series, and wherein theelectrical contacts comprise: a first concentric electrical contactelectrically connected between the first and second RC pairs; a secondconcentric electrical contact electrically connected to a first end ofthe first and second RC pairs in series; and a third concentricelectrical contact electrically connected to a second end of the firstand second RC pairs in series; wherein the analyte sensor comprises aworking electrode and counter electrode, the working electrode coupledto the second concentric electrical contact, and the counter electrodecoupled to the third concentric electrical contact.
 4. The analytemonitoring system of claim 1, wherein the on-body housing iscone-shaped.
 5. The analyte monitoring system of claim 4, wherein theelectronic circuitry comprises first and second RC pairs in series, andwherein the electrical contacts comprise: a first concentric electricalcontact electrically connected between the first and second RC pairs; asecond concentric electrical contact electrically connected to a firstend of the first and second RC pairs in series; and a third concentricelectrical contact electrically connected to a second end of the firstand second RC pairs in series; wherein the analyte sensor comprises aworking electrode and counter electrode, the working electrode coupledto the second concentric electrical contact, and the counter electrodecoupled to the third concentric electrical contact.
 6. The analytemonitoring system of claim 1, wherein the electrical contacts comprisefirst, second, and third concentric electrical contacts disposed on anexternal surface of the on the on-body housing.
 7. The analytemonitoring system of claim 1, wherein the on-body housing comprises abase perimeter with flat edges.
 8. The analyte monitoring system ofclaim 1, wherein the on-body housing comprises a recessed baseperimeter.
 9. The analyte monitoring system of claim 1, wherein theelectronic circuitry comprises first and second RC pairs in series, andwherein the electrical contacts comprise: a first concentric electricalcontact electrically connected between the first and second RC pairs; asecond concentric electrical contact electrically connected to a firstend of the first and second RC pairs in series; and a third concentricelectrical contact electrically connected to a second end of the firstand second RC pairs in series; wherein the analyte sensor comprises aworking electrode and counter electrode, the working electrode coupledto the second concentric electrical contact, and the counter electrodecoupled to the third concentric electrical contact.
 10. The analytemonitoring system of claim 9, wherein the OBU comprises isolatedcontacts for performing continuity measurements, wherein the isolatedcontacts are disposed on the on-body housing and isolated from the firstand second RC pairs.
 11. The analyte monitoring system of claim 10,wherein the first, second, and third concentric electrical contacts arering-shaped, and wherein the isolated contacts are disposed within allthree concentric electrical contacts.
 12. The analyte monitoring systemof claim 11, wherein each isolated contact is ring-shaped andconcentrically disposed.
 13. The analyte monitoring system of claim 1,wherein the electronic circuitry is at least partially powered by theanalyte sensor.
 14. The analyte monitoring system of claim 1, whereinthe analyte sensor is a glucose sensor or a ketone sensor.
 15. A method,comprising: positioning an on-body unit (OBU) on a skin surface, the OBUcomprising: a transcutaneous analyte sensor; electronic circuitrycoupled to the analyte sensor; and an on-body housing comprising asubstantially flat surface and a curved and convex surface opposite thesubstantially flat surface, wherein the on-body housing has electricalcontacts disposed on the curved and convex surface, the electricalcontacts electrically coupled to the electronic circuitry; physicallycontacting a hand-held reader to the OBU, wherein the hand-held readercomprises a plurality of electrical contacts that electrically couple tothe electrical contacts on the on-body housing when the readerphysically contacts the on-body housing; and transmitting an analytesensor signal from the OBU to the reader via the electrical contacts onthe on-body housing and the plurality of electrical contacts on thereader, wherein the analyte sensor signal corresponds to an analyteconcentration level.
 16. The method of claim 15, wherein the on-bodyhousing is dome-shaped.
 17. The method of claim 16, wherein theelectronic circuitry comprises first and second RC pairs in series, andwherein the electrical contacts comprise: a first concentric electricalcontact electrically connected between the first and second RC pairs; asecond concentric electrical contact electrically connected to a firstend of the first and second RC pairs in series; and a third concentricelectrical contact electrically connected to a second end of the firstand second RC pairs in series; wherein the analyte sensor comprises aworking electrode and counter electrode, the working electrode coupledto the second concentric electrical contact, and the counter electrodecoupled to the third concentric electrical contact.
 18. The method ofclaim 15, wherein the on-body housing is cone-shaped.
 19. The method ofclaim 18, wherein the electronic circuitry comprises first and second RCpairs in series, and wherein the electrical contacts comprise: a firstconcentric electrical contact electrically connected between the firstand second RC pairs; a second concentric electrical contact electricallyconnected to a first end of the first and second RC pairs in series; anda third concentric electrical contact electrically connected to a secondend of the first and second RC pairs in series; wherein the analytesensor comprises a working electrode and counter electrode, the workingelectrode coupled to the second concentric electrical contact, and thecounter electrode coupled to the third concentric electrical contact.20. The method of claim 15, wherein the electrical contacts comprisefirst, second, and third concentric electrical contacts disposed on anexternal surface of the on the on-body housing.
 21. The method of claim15, wherein the on-body housing comprises a base perimeter with flatedges.
 22. The method of claim 15, wherein the on-body housing comprisesa recessed base perimeter.
 23. The method of claim 15, wherein theelectronic circuitry comprises first and second RC pairs in series, andwherein the electrical contacts comprise: a first concentric electricalcontact electrically connected between the first and second RC pairs; asecond concentric electrical contact electrically connected to a firstend of the first and second RC pairs in series; and a third concentricelectrical contact electrically connected to a second end of the firstand second RC pairs in series; wherein the analyte sensor comprises aworking electrode and counter electrode, the working electrode coupledto the second concentric electrical contact, and the counter electrodecoupled to the third concentric electrical contact.
 24. The method ofclaim 23, wherein the OBU comprises isolated contacts for performingcontinuity measurements, wherein the isolated contacts are disposed onthe on-body housing and isolated from the first and second RC pairs. 25.The method of claim 24, wherein the first, second, and third concentricelectrical contacts are ring-shaped, and wherein the isolated contactsare disposed within all three concentric electrical contacts.
 26. Themethod of claim 25, wherein each isolated contact is ring-shaped andconcentrically disposed.
 27. The method of claim 15, wherein theelectronic circuitry is at least partially powered by the analytesensor.
 28. The method of claim 15, wherein the analyte sensor is aglucose sensor or a ketone sensor.